Japan is a very polite society, however as a very hierachical society it can sometimes be much less polite than you might think. Essentially politeness always goes up, younger or more junior
people show respect to their elders and seniors who are not obliged to be polite in return. The Japanese language has many ways to show the subtle shades of hierarchy, respect and politeness that
can be a minefield even to Japanese people.
However as a tourist you are a guest and/or a customer and as such you will be shown great politeness and you are not expected to reciprocate to the same degree. Simple courtesies such as saying please 'onegai shimasu' (o ne gai shi mas) and thank you 'arigato' is enough.
You might not have any great need to bow very much while you are in Japan, but if you do it is best to know how to do it.
Bowing has many degrees from a simple nod to getting down on your knees and touching your forehead on the floor. Japanese people are taught how to bow correctly when they join a company, it's taken very seriously, but as a guest you just need to remember some basics.
Bow from the waist. If only your head is moving then its a nod, not a bow. You don't need to go low, but make sure that your shoulders move! Nods do have a use though, when you recognise a casual acquaintance on the street for example.
What do you do with your hands?
In formal situations women fold their hands in front of their stomachs, whilst men hold their arms stiff by their sides. As long as your arms dont dangle loosly in front of you it doesn't really matter!
How far do you bow?
This depends, if you are meeting someone important then somewhere between 45 an 90 degrees according to how important they are. Apologies and thank you's similarly depend on the level of apology
or gratitude being shown, so use common sense.
As a visitor, you are not expected to get it perfect, but the effort will be appreciated.
Japanese table manners are quite different from the west. Slurping your noodles is polite, as is holding your rice bowl or plate as you eat.
Traditionally Japanese people hate to leave food, so try to clear your plate especially if you are a guest.
Before you eat you should say "ita daki mas". This has no religious significance but shows respect for the food.
When you finish you should say "go chi so sa ma". This shows appreciation for the food.
Chopsticks have their own set of rules, but most of them are common sense so don't wave your chopsticks around or use them to mix your drink. The big taboo is to stick your chopsticks vertically in a rice bowl or other dish. This is done at funerals and thus is associated with death.
Drinking is a big part of Japanese culture so join in!
The golden rule when drinking in Japan is not to pour your own drinks, if there is a bottle of beer, wine or sake on the table you should be sure to keep your neighbors glass topped up and they will do the same for you. This can lead to you drinking far more than you want to, so do be careful. Whilst some Japanese people really can't hold their drinks it's by no means universal and some Japanese people can drink you under the table.
If you have had enough, simply put your hand over your glass.
If you are drinking in a bar with beer on tap then these rules don't apply.
At formal events you should wait for the toast or 'kanpai' before you start drinking.
Japanese people are fairly easy going, but living on a crowded island where most of the land is mountainous has created the mega-cities where the majority of the population live. By necessity Japanese people have learned how to live in relative harmony and this is a major part of what some people call the Japanese psyche.
Put simply, Japanese people are hyper aware of the people around them and the need to avoid creating a 'meiwaku' or nuisance.
Developing a similar mentality of consideration and concern for others is the best way to fit into Japan and to take something of Japans famous 'wa' or harmony back to your home country.